Again, the actual yield is not enormous, and the yield is still
back where Japan was a year ago, and not even that much higher
than it was in the beginning of 2013.

But when you have a country that's famously so much in debt, this
kind of volatility in such a short time makes people queasy.

All that being said, rising yields are a generally good sign.
Japan's primary battle is about fighting deflation, and reversing
the years and years of declining rates that have coincided with a
weakening economy. So just like other markets that have been
shocked into a reversal, JGBs are seeing a similar phenomenon.

But without a doubt, this is the market that's got people paying
the most attention.